Lettuce confirmed as source of E coli outbreak

May 11, 2010 (CIDRAP News) – Federal investigation of an outbreak of a rare strain of Escherichia coli expanded yesterday as researchers confirmed a link between the strain, E coli O145, and the bagged shredded lettuce suspected of spreading it.

The US Food and Drug Administration (FDA) said late yesterday that the New York State Public Health Laboratory found the outbreak strain in an unopened bag of shredded romaine distributed by Freshway Foods of Sidney, Ohio. The connection between the food and the pathogen had been suspected since last week, when increasing evidence of an epidemiologic connection between the two led Freshway to voluntarily recall 72 different types of bagged lettuce sold to wholesalers and food-service outlets in 23 states.

The count of confirmed cases in the outbreak remains at 19 in Michigan, New York, and Ohio, according to the FDA. Twelve patients have been hospitalized and three have developed hemolytic uremic syndrome, a potentially fatal impairment of the kidneys. According to the Centers for Disease Control and Prevention (CDC), 10 additional cases are believed to be linked to the outbreak.

Meanwhile, a second firm has launched a recall of romaine lettuce because it was harvested on the same Yuma, Ariz., farm that grew the Freshway lettuce, the FDA said. Vaughan Foods of Moore, Okla., said it was recalling bagged romaine with a sell-by date of either May 9 or May 10; the Freshway recall covers sell-by dates up to May 12.

In another twist, the Columbus Dispatch reported that the Ohio Department of Agriculture has also tested bagged lettuce implicated in the outbreak and found a second, unrelated strain of E coli in a bag of shredded romaine from Freshway. That discovery caused another company, the Andrew Smith Co. of California, to launch its own recall of 1,000 cartons or about 23,000 pounds of lettuce sold to Vaughan Foods and to an unidentified third firm in Massachusetts. The Smith Co. buys lettuce from farms and sells it to processors who then distribute it to food-service outlets.

The company told the Dispatch that Freshway is a customer but had not received any of the lettuce recalled by Smith.

The ongoing investigation has been hampered by the small amount of surveillance performed for the O145 strain, which, like the more famous E coli O157:H7, produces Shiga toxin and causes abdominal cramps and bloody diarrhea that can last for a week and lead to serious complications. The CDC said last week that many clinical laboratories do not test for O145 because the assay is more difficult to perform, and that therefore cases caused by the strain may be underreported.

The expanding outbreak demonstrates that it is time to begin surveillance and testing for O145 and other Shiga toxin–producing E coli strains, food-safety attorney Bill Marler said in an interview.

Marler, who has filed a suit on behalf of one of the O145 victims, is the lead author of a petition that asks the federal government to consider non-O157 strains of E coli to be meat "adulterants," a legal classification that would trigger recall notices and also surveillance and testing. Currently, only O157:H7 has that classification.

"Over the years, outbreaks of non-O157 strains have been infrequent, but that infrequency has more to do with the fact that we are not testing for it than that it does not occur," he said. "Because there is not much data, the government is not acting."